1. Field of the Invention
This application relates generally to a user recognition system and a method thereof, and more particularly to a user recognition system recognizing a user from an input facial and/or other bodily feature image(s) and a method thereof.
2. Description of the Prior Art
Concerning communication and interaction between a human and a robot, it is vital for the robot to recognize a human. With such a capability to recognize, the robot can authorize a recognized user and may provide customized service for each recognized individual user.
The biometrics technology, which is based on the physical and behavioral features of a human body, is considered to be a very promising method of recognizing a user. There are several biometrics methods including face recognition, voice recognition, gait recognition, etc. that are applied to recognize a user by a robot or a machine. The face recognition is the most commonly used human recognition method implemented in a robot system or machine since a user need not come in close contact with the machine, and thus the face recognition method is advantageous for its ability for remote recognition.
Similar to other recognition methods, the face recognition method has been studied for its use in security systems. Many types of the face recognition method that have been studied up to now are broadly classified into the feature matching algorithm and the template matching algorithm. The mainstream face recognition methods include Principal Component Analysis (PCA), Elastic Bunch graph matching, Linear Discrimination Analysis (LDA), and Local Feature Analysis (LFA), and various studies have proven that all these given methods are highly effective in face recognition.
However, as it has been revealed from the various studies, the above-mentioned face recognition methods are vulnerable to environmental factors such as lighting conditions and pose variations of a user. These studies that achieved excellent recognition performance results in face recognition were conducted under a well-controlled environment (i.e., consistent lighting, front face, etc.). Under the well-controlled environment, a user to be recognized by a robot would face the robot in front, and the lighting conditions would be similar to the lighting conditions when the user is enrolled by the robot.
However, the lighting conditions and the user poses will vary in an environment where humans and a mobile robot dynamically interact with each other, and thus it is difficult to maintain the same lighting condition and pose. A conventional face recognition method focused on a security system requires a user to be cooperative. However, it would be difficult to expect a user to look for a robot and to become cooperative when the robot continually monitors the images in order to recognize the user identifications.
Although there are various conventional methods dealing with recognition of facial appearances under varying lighting and user pose conditions, the process for carrying out the conventional methods is too complex and difficult to realize in real-time.
Any effective face recognition method has to overcome the expected and problematic environmental variations when the method is applied to a mobile robot.
The disclosure in this Background section is intended only for enhancement of understanding of the background of the invention and may contain information that are not prior art.